We went to a planetarium last night last night and watched "Black Holes" narrated by Liam Neeson. If I recall correctly, he said that scientists believe that they have identified a number of Black Holes, and that they think there are White Holes at the bottom of Black Holes and instead of drawing matter/light in, the White Holes spew matter out. I didn't get to ask this question after the session was over: Have scientists been able to find an example of a possible White Hole?

@Andrew: No, the Big Bang was not a white hole. One way to see this is that an FLRW spacetime is homogeneous, whereas a Schwarzschild spacetime has only rotational symmetry.
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Ben CrowellJul 12 '13 at 18:20